Thin film transistors (TFTs) have been widely used as driving elements in the flat-panel display technology due to such advantages as small volume, low power consumption and low manufacture cost.
For a TFT display device, each TFT of the TFT display device is turned on or off under the control of a gate line. When the TFT is turned on, a pixel voltage is applied to a corresponding pixel via a data line. A charge rate of a pixel is defined as a ratio of the pixel voltage applied to the pixel to a voltage applied to the data line, and the pixel voltage is related to a charge time and a turn-on current of the TFT. Taking a display device with a refresh rate of 120 Hz and a resolution of 3840*2160 pixels as an example, the pixels in each row are charged for a charge time t of 3.7 μs (t=1/120/2220 (60 rows of blank regions)). Within 3.7 μs, an amorphous-silicon (a-Si) TFT has relatively low carrier mobility, so it is impossible to fully charge the pixel within a short time period. At this time, the pixel voltage may be smaller than the voltage applied to the data line.